Medium protection in wireless local area networks

ABSTRACT

A communication device determines whether a PHY data unit is to be transmitted in a first frequency band from among multiple frequency bands in which a WLAN communication protocol permits operation. The multiple frequency bands also include a second frequency band. The communication device determines whether the PHY data unit is to include a PS-Poll frame, and whether a BSS color is currently disabled for the WLAN. In response to i) determining that the PHY data unit is to be transmitted in the first frequency band, ii) determining that the PHY data unit is not to include a PS-Poll frame, and iii) determining that the BSS color is not currently disabled for the WLAN: the communication device determines that a TXOP duration subfield in a PHY preamble of the PHY data unit cannot be set to a value defined by the WLAN communication protocol for indicating a TXOP duration that is unspecified.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/526,753 (now U.S. Pat. No. 10,959,229), entitled “Medium Protectionin Wireless Local Area Networks,” filed Jul. 30, 2019, which claims thebenefit of the following U.S. Provisional Patent Applications:

U.S. Provisional Patent Application No. 62/712,084, entitled “HighEfficiency (HE) Operation at 6 GHz Band,” filed on Jul. 30, 2018;

U.S. Provisional Patent Application No. 62/722,070, entitled “HighEfficiency (HE) Operation at 6 GHz Band,” filed on Aug. 23, 2018;

U.S. Provisional Patent Application No. 62/736,907, entitled “HighEfficiency (HE) Operation at 6 GHz Band,” filed on Sep. 26, 2018; and

U.S. Provisional Patent Application No. 62/792,306, entitled “HighEfficiency (HE) Operation at 6 GHz Band,” filed on Jan. 14, 2019.

Additionally, this application is related to U.S. patent applicationSer. No. 16/526,808 (now U.S. Pat. No. 10,952,216), entitled “WirelessLocal Area Network Management,” filed Jul. 30, 2019.

The disclosures of all of the above-referenced patent applications arehereby incorporated by reference herein in their entireties.

FIELD OF TECHNOLOGY

The present disclosure relates generally to wireless communicationsystems, and more particularly to protecting transmissions in a wirelesscommunication network.

BACKGROUND

Wireless local area networks (WLANs) have evolved rapidly over the pasttwo decades, and development of WLAN standards such as the Institute forElectrical and Electronics Engineers (IEEE) 802.11 Standard family hasimproved single-user peak data throughput. For example, the IEEE 802.11bStandard specifies a single-user peak throughput of 11 megabits persecond (Mbps), the IEEE 802.11a and 802.11g Standards specify asingle-user peak throughput of 54 Mbps, the IEEE 802.11n Standardspecifies a single-user peak throughput of 600 Mbps, and the IEEE802.11ac Standard specifies a single-user peak throughput in thegigabits per second (Gbps) range. The IEEE 802.11ax Standard now in thefinal stages of development significantly improves throughput over theIEEE 802.11ac Standard.

Communications between communication devices in a WLAN may occur duringa transmit opportunity (TXOP) during which one of more frame exchangesare preformed between a communication device and one or more othercommunications devices. In a typical WLAN in which multiple frameexchanges are performed during a TXOP, a bandwidth of a frame exchangeduring a TXOP can be reduced relative of a bandwidth of a previous frameexchange during the TXOP. However, in a typical WLAN, a bandwidth of aframe exchange during a TXOP cannot be increased in a following frameexchange in the TXOP unless the TXOP is protected by an initialrequest-to-send (RTS)/clear-to-send (CTS) frame exchange performed atthe beginning of the TXOP.

SUMMARY

In an embodiment, a method for communicating in a wireless local areanetwork (WLAN) includes: determining, at a communication device, whethera physical layer (PHY) data unit is to be transmitted in a firstfrequency band from among multiple frequency bands in which a WLANcommunication protocol permits operation, wherein the multiple frequencybands includes at least a second frequency band; determining, at thecommunication device, whether the PHY data unit is to include a powersave poll (PS-Poll) frame; determining, at the communication device,whether a basic service set (BSS) color is currently disabled for theWLAN; in response to i) determining that the PHY data unit is to betransmitted in the first frequency band, ii) determining that the PHYdata unit is not to include a PS-Poll frame, and iii) determining thatthe BSS color is not currently disabled for the WLAN: determining, atthe communication device, that a transmit opportunity (TXOP) durationsubfield in a PHY preamble of the PHY data unit cannot be set to a valuedefined by the WLAN communication protocol for indicating a TXOPduration that is unspecified, and generating, at the communicationdevice, the PHY data unit so that the TXOP duration subfield is set to aduration value that is different than the value defined by the WLANcommunication for indicating the TXOP duration that is unspecified. Themethod also includes transmitting, by the communication device, the PHYdata unit in the first frequency band.

In another embodiment, a communication device comprises a wirelessnetwork interface device having one or more integrated circuit (IC)devices. The wireless network interface is configured to: determinewhether a PHY data unit is to be transmitted in a first frequency bandfrom among multiple frequency bands in which a WLAN communicationprotocol permits operation, wherein the multiple frequency bandsincludes at least a second frequency band; determine whether the PHYdata unit is to include a PS-Poll frame; determine whether a BSS coloris currently disabled for a WLAN in which the communication device isoperating; and in response to i) determining that the PHY data unit isto be transmitted in the first frequency band, ii) determining that thePHY data unit is not to include a PS-Poll frame, and iii) determiningthat the BSS color is not currently disabled for the WLAN: determinethat a TXOP duration subfield in a PHY preamble of the PHY data unitcannot be set to a value defined by the WLAN communication protocol forindicating a TXOP duration that is unspecified, and generate the PHYdata unit so that the TXOP duration subfield is set to a duration valuethat is different than the value defined by the WLAN communication forindicating the TXOP duration that is unspecified. The wireless networkinterface is further configured to transmit the PHY data unit in thefirst frequency band.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example wireless local area network(WLAN), according to an embodiment.

FIG. 2 is a block diagram of an example physical layer (PHY) data unittransmitted by communication devices in the WLAN of FIG. 1 , accordingto an embodiment.

FIG. 3 is a block diagram of another example physical layer (PHY) dataunit transmitted by communication devices in the WLAN of FIG. 1 ,according to an embodiment.

FIG. 4A is a diagram of an example transmission sequence that occursduring a TXOP in the WLAN 110 of FIG. 1 , according to an embodiment.

FIG. 4B is a diagram of another example transmission sequence thatoccurs during a TXOP in the WLAN 110 of FIG. 1 , according to anotherembodiment.

FIG. 4C is a diagram of yet another example transmission sequence thatoccurs during a TXOP in the WLAN 110 of FIG. 1 , according to yetanother embodiment.

FIG. 5 is a diagram of an example transmission sequence in whichmultiple frame exchanges occur during a TXOP in the WLAN 110 of FIG. 1 ,according to another embodiment.

FIG. 6 is a diagram of another example transmission sequence in whichmultiple frame exchanges occur during a TXOP in the WLAN 110 of FIG. 1 ,according to an embodiment.

FIG. 7A is a diagram illustrating an example scheme of associationservice periods used in the WLAN 110 of FIG. 1 , according to anembodiment.

FIG. 7B is a diagram illustrating another example scheme of associationservice periods used in the WLAN 110 of FIG. 1 , according to anembodiment.

FIG. 8 is a flow diagram of an example method, implemented in the WLANof FIG. 1 , for transmitting multiple data units in a communicationchannel, according to an embodiment.

DETAILED DESCRIPTION

In embodiments described below, a wireless communication device such asan access point (AP) or a client station in a wireless network, such asa wireless local area network (WLAN) managed by the AP, is configured tooperate i) in at least a first frequency band and ii) according to atleast a first communication protocol. For example, in an embodiment, thefirst communication protocol is the IEEE 802.11ax Standard, now in thefinal stages of being standardized, and the first frequency band is a 6GHz band (5.925 to 7.125 GHz) recently released by the FederalCommunication Commission (FCC) for WLAN operation. In some embodiments,the wireless communication device is additionally configured to operatei) in a second frequency band and/or a third frequency band and/or ii)according to a second communication protocol, according to a thirdcommunication protocol and/or according to a fourth communicationprotocol. For example, in an embodiment, the second frequency band isthe 5 GHz band (approximately 5.170 to 5.835 GHz) and the thirdfrequency band is the 2.4 GHz band (approximately 2.4 to 2.5 GHz). As anexample, in an embodiment, the second communication protocol is the IEEE802.11ac Standard, the third communication protocol is the IEEE 802.11nStandard, and the fourth communication protocol is the IEEE 802.11aStandard. The second communication protocol, the third communicationprotocol and the fourth communication protocol are legacy communicationprotocols with respect to the first communication protocol, in anembodiment. The fourth communication protocol is legacy with respect tothe first communication protocol, the second communication protocol, andthe third communication protocol, in an embodiment. In an embodiment,transmissions (e.g., data units that include control information,management information and/or data) that conform to the firstcommunication protocol (e.g., conform to a physical layer data unitformat specified by the first communication protocol) and transmissions(e.g., at least data units that include control information) thatconform to the fourth communication protocol (e.g., conform to aphysical layer data unit format specified by the fourth communicationprotocol) are allowed in the first frequency band. On the other hand,transmissions (e.g., data units that include control information,management information and/or data) that conform to the secondcommunication protocol (e.g., conform to a physical layer data unitformat specified by the second communication protocol) and transmissions(e.g., data units that include control information, managementinformation and/or data) that conform to the third communicationprotocol (e.g., conform to a physical layer data unit format specifiedby the third communication protocol) are not allowed in the firstfrequency band, in an embodiment.

In various embodiments, the communication device (e.g., the AP or theclient station) transmits various control frames, such asrequest-to-send (RTS) frames, clear-to-send (CTS) frames, triggerframes, acknowledgement frames, etc. Control frames are utilized toassist with transmission of data, for example by reserving acommunication channel for data transmissions to protect the datatransmissions from potential collisions with transmissions by othercommunication devices, in an embodiment. In current WLANs, such controlframes are typically transmitted using physical layer data units thatconform to a legacy physical layer data unit format (e.g., a physicallayer data unit format specified by the fourth communication protocol)and using legacy control frame transmission rules (e.g., as specified bythe fourth communication protocol) to allow legacy communication devicesto receive and decode the data unit that include the control frames. Insome embodiments described below, physical layer data unit format usedfor transmission of at least some types of control frames depends onwhether the control frames are transmitted in the first frequency bandor transmitted in the second or third frequency. For example, thecommunication device selectively utilizes the legacy physical layer dataunit format and the legacy control frame transmission rules specified bythe fourth communication protocol when transmitting a control frame inthe first frequency band, the second frequency band or the thirdfrequency band, and, additionally, utilizes non-legacy physical layerdata unit formats and/or non-legacy transmission rules specified by thefirst communication protocol in at least some situations whentransmitting the control frame in the first frequency band. In somesituations, transmission of the control frame using non-legacy physicallayer data unit formats and/or non-legacy transmission rules whentransmitting the control frame in the first frequency band results inmore robust transmission of the control frame in the first frequencyband, for example, as compared to transmission of the control frames inthe second frequency band and/or the third frequency band, in at leastsome embodiments. In some situations, transmission of the control frameusing non-legacy physical layer data unit formats and/or non-legacytransmission rules when transmitting the control frame in the firstfrequency band additionally or alternatively results in more efficienttransmission of the control frame in the first frequency band, forexample, as compared to transmission of the control frames in the secondfrequency band and/or the third frequency band, in at least someembodiments.

In various embodiments, the communication device (e.g., the AP or theclient station) transmits multiple frames to at least one othercommunication device during a transmit opportunity (TXOP) obtained bythe communication device. In current WLANs, when multiple frameexchanges occur during a TXOP, the bandwidth of any frame exchangecannot be greater than the bandwidth of an immediately preceding frameexchange in the TXOP unless the TXOP is protected by an initial controlframe exchange (e.g., a request-to-send (RTS)/clear-to-send (CTS) frameexchange), that conforms to a legacy communication protocol (e.g., thefourth communication protocol) and that occurred prior to transmissionof the multiple frames during the TXOP. Thus, for example, if abandwidth of a second frame exchange during the TXOP is decreased withrespect to a bandwidth of a first frame exchange that occurred prior tothe second exchange during the TXOP, a bandwidth of any consequent frameexchange during the TXOP cannot be greater than the reduced bandwidth ofthe second frame exchange of the TXOP unless the TXOP is protected by aninitial RTS/CTS frame exchange, that conforms to the fourthcommunication protocol, prior to transmission of the multiple frames. Inembodiments described below, TXOP communication channel protectionmechanisms allow for a reduced bandwidth of a frame exchange during aTXOP to be increased in a following frame exchange in the TXOP in atleast some situations in which the TXOP is not protected by an initialRTS/CTS frame exchange that conforms to the fourth communicationprotocol, at least for operation in the first frequency band. Thus, forexample, transmission of an initial RTS/CTS frame exchange is notrequired in order to allow for a reduced bandwidth of a frame exchangeduring the TXOP to be increased in a following frame exchange in theTXOP, at least in the first frequency band, in an embodiment.

FIG. 1 is a block diagram of an example wireless local area network(WLAN) 110, according to an embodiment. The WLAN 110 includes an accesspoint (AP) 114 that comprises a host processor 118 coupled to a networkinterface device 122. The network interface device 122 includes one ormore medium access control (MAC) processors 126 (sometimes referred toherein as “the MAC processor 126” for brevity) and one or more physicallayer (PHY) processors 130 (sometimes referred to herein as “the PHYprocessor 130” for brevity). The PHY processor 130 includes a pluralityof transceivers 134, and the transceivers 134 are coupled to a pluralityof antennas 138. Although three transceivers 134 and three antennas 138are illustrated in FIG. 1 , the AP 114 includes other suitable numbers(e.g., 1, 2, 4, 5, etc.) of transceivers 134 and antennas 138 in otherembodiments. In some embodiments, the AP 114 includes a higher number ofantennas 138 than transceivers 134, and antenna switching techniques areutilized.

In an embodiment, the network interface device 122 is configured foroperation within a single RF band at a given time. In anotherembodiment, the network interface device 122 is configured for operationwithin two or more RF bands at the same time or at different times. Inan embodiment, the network interface device 122 implements multiple APs(e.g., co-located APs), respective APs operating in respective ones ofthe frequency bands. For example, in an embodiment, the networkinterface device 122 includes multiple PHY processors 130, whererespective PHY processors 130 correspond to respective ones of theco-located APs for operation in respective ones of the frequency bands.In another embodiment, the network interface device 122 includes asingle PHY processor 130, where each transceiver 134 includes respectiveRF radios corresponding to respective ones of the co-located APs foroperation in respective ones of the frequency bands. In an embodiment,the network interface device 122 includes multiple MAC processors 126,where respective MAC processors 126 correspond to respective ones of theco-located APs for operation in respective ones of the frequency bands.In another embodiment, the network interface device 122 includes asingle MAC processor 126 corresponding to the multiple co-located APsfor operation in respective ones of the frequency bands.

The network interface device 122 is implemented using one or moreintegrated circuits (ICs) configured to operate as discussed below. Forexample, the MAC processor 126 may be implemented, at least partially,on a first IC, and the PHY processor 130 may be implemented, at leastpartially, on a second IC. The first IC and the second IC may bepackaged together in a single IC package thereby forming a modulardevice, or the first IC and the second IC may be coupled together on asingle printed board, for example, in various embodiments. As anotherexample, at least a portion of the MAC processor 126 and at least aportion of the PHY processor 130 may be implemented on a single IC. Forinstance, the network interface device 122 may be implemented using asystem on a chip (SoC), where the SoC includes at least a portion of theMAC processor 126 and at least a portion of the PHY processor 130.

In an embodiment, the host processor 118 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a random access memory (RAM), a read-only memory (ROM), aflash memory, etc. In an embodiment, the host processor 118 may beimplemented, at least partially, on a first IC, and the network device122 may be implemented, at least partially, on a second IC. As anotherexample, the host processor 118 and at least a portion of the networkinterface device 122 may be implemented on a single IC.

In various embodiments, the MAC processor 126 and/or the PHY processor130 of the AP 114 are configured to generate data units, and processreceived data units, that conform to a WLAN communication protocol suchas a communication protocol conforming to the IEEE 802.11 Standard oranother suitable wireless communication protocol. For example, the MACprocessor 126 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 130 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. Forinstance, the MAC processor 126 may be configured to generate MAC layerdata units such as MAC service data units (MSDUs), MAC protocol dataunits (MPDUs), etc., and provide the MAC layer data units to the PHYprocessor 130. The PHY processor 130 may be configured to receive MAClayer data units from the MAC processor 126 and encapsulate the MAClayer data units to generate PHY data units such as PHY protocol dataunits (PPDUs) for transmission via the antennas 138. Similarly, the PHYprocessor 130 may be configured to receive PHY data units that werereceived via the antennas 138, and extract MAC layer data unitsencapsulated within the PHY data units. The PHY processor 130 mayprovide the extracted MAC layer data units to the MAC processor 126,which processes the MAC layer data units.

PHY data units are sometimes referred to herein as “packets”, and MAClayer data units are sometimes referred to herein as “frames”.

In connection with generating one or more radio frequency (RF) signalsfor transmission, the PHY processor 130 is configured to process (whichmay include modulating, filtering, etc.) data corresponding to a PPDU togenerate one or more digital baseband signals, and convert the digitalbaseband signal(s) to one or more analog baseband signals, according toan embodiment. Additionally, the PHY processor 130 is configured toupconvert the one or more analog baseband signals to one or more RFsignals for transmission via the one or more antennas 138.

In connection with receiving one or more RF signals, the PHY processor130 is configured to downconvert the one or more RF signals to one ormore analog baseband signals, and to convert the one or more analogbaseband signals to one or more digital baseband signals. The PHYprocessor 130 is further configured to process (which may includedemodulating, filtering, etc.) the one or more digital baseband signalsto generate a PPDU.

The PHY processor 130 includes amplifiers (e.g., a low noise amplifier(LNA), a power amplifier, etc.), a radio frequency (RF) downconverter,an RF upconverter, a plurality of filters, one or more analog-to-digitalconverters (ADCs), one or more digital-to-analog converters (DACs), oneor more discrete Fourier transform (DFT) calculators (e.g., a fastFourier transform (FFT) calculator), one or more inverse discreteFourier transform (IDFT) calculators (e.g., an inverse fast Fouriertransform (IFFT) calculator), one or more modulators, one or moredemodulators, etc.

The PHY processor 130 is configured to generate one or more RF signalsthat are provided to the one or more antennas 138. The PHY processor 130is also configured to receive one or more RF signals from the one ormore antennas 138.

The MAC processor 126 is configured to control the PHY processor 130 togenerate one or more RF signals, for example, by providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 130, andoptionally providing one or more control signals to the PHY processor130, according to some embodiments. In an embodiment, the MAC processor126 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a readROM, a flash memory, etc. In another embodiment, the MAC processor 126includes a hardware state machine.

The MAC processor 126 includes, or implements, a medium protectioncontroller 142. The medium protection controller 142 implements mediumprotection mechanisms of the AP 114 in at least the first frequency band(e.g., the 6 GHz band). In some embodiments, the medium protectioncontroller 142 additionally implements medium protection mechanisms ofthe AP 114 in one or more additional frequency bands, such as the secondfrequency band (e.g., the 5 GHz band) and/or the third frequency band(e.g., the 2.4 GHz band).

As will be described in more detail below, the medium protectioncontroller 142 generates a control frame (e.g., an RTS, a CTS frame, atrigger frame, an acknowledgement frame, etc.), and prompts the PHYprocessor 130 to transmit the control frame to one or more clientstations 154, for example to reserve a communication channel fortransmissions between the AP 114 and the one or more client stations154. In an embodiment, the medium protection controller 142 prompts thePHY processor 130 to transmit the control frame using a particular PHYdata unit format and/or particular transmission rules, where theparticular PHY data unit format and/or the particular transmission rulesdepend on the particular frequency band in which the control frame is tobe transmitted. For example, when the control frame is to be transmittedin the second frequency band or in the third frequency band, the mediumprotection controller 142 prompts the PHY processor 130 to transmit thecontrol frame using a legacy PHY data unit format (e.g., a PHY data unitformat specified by the fourth communication protocol) and legacytransmission rules (e.g., specified by the fourth communicationprotocol). On the other hand, when the control frame is to betransmitted in the first frequency band, the medium protectioncontroller 142 selectively prompts the PHY processor 130 to transmit thecontrol frame i) using a legacy PHY data unit format (e.g., a PHY dataunit format specified by the fourth communication protocol) and legacytransmission rules or ii) using a non-legacy PHY data unit format and/ornon-legacy transmission rules. Transmission of the control frame usingnon-legacy PHY data unit formats and/or non-legacy transmission rules inthe first frequency band results in more efficient and/or more robusttransmission of the control frame in the first frequency band, forexample, as compared to transmission of control frames in the secondfrequency band and in the third frequency band, in at least someembodiments.

Permitting the PHY format that conforms to the fourth communicationprotocol for transmission of control frames simplifies implementation ofmultiple co-located communication devices (e.g., APs or client stations)within a single communication device, in an embodiment. For example, inan embodiment in which control frames are transmitted using the PHYformat that conforms to the fourth communication protocol in the secondfrequency and and/or the third frequency band, permitting the PHY formatthat conforms to the fourth communication protocol for transmission ofcontrol frames in the first frequency band facilitate the use of asingle MAC processor of the communication device to implement MACfunctions for operation of multiple co-located communication devices i)in the first frequency band and ii) in the second and/or third frequencyband, in at least some embodiments.

In an embodiment, the medium protection controller 142 generatesmultiple frames (e.g., control, management and/or data frames), andprompts the PHY processor to transmit the multiple frames to one or moreclient stations 154 during a transmit opportunity (TXOP) fortransmissions between the AP 114 and one or more client stations 154-1.In an embodiment, the medium protection controller 142 determines abandwidth to be used for transmission of a frame of the multiple frames,and prompts the PHY processor 130 to transmit the frame using a PHY dataunit that spans the determined bandwidth of the frame. As will beexplained in more detail below, in at least some situations, the mediumprotection controller 142 determines that a bandwidth of a frame to betransmitted during the TXOP can be increased with respect to a bandwidthof a previous frame transmitted during the TXOP in at least somesituations in which the TXOP is not protected by an initial controlframe exchange, that conforms to a legacy communication protocol (e.g.,the fourth communication protocol), prior to transmission of themultiple frames during the TXOP. For example, in an embodiment, themedium protection controller 142 determines that the wider bandwidth hasbeen reserved for transmissions between the AP 114 and the one or moreclient stations 154, for the duration of the TXOP, by previoustransmissions of non-legacy data units during the TXOP. In at least somesuch situations, the medium protection controller 142 generates theframe for transmission in the wider bandwidth, and prompts the PHYprocessor 130 to transmit the frame using a PHY data unit that spans thedetermined wider bandwidth. Because the bandwidth of a frame transmittedduring a TXOP is increased with respect to the bandwidth of a previouslytransmitted frame during the TXOP even if the TXOP is not protected byan initial control frame exchange, that conforms to a legacycommunication protocol (e.g., the fourth communication protocol), priorto transmission of the multiple frames during the TXOP, more information(e.g., management information, data, etc.) can be transmitted during theTXOP as compared to systems in which frame bandwidth cannot be increasedduring the TXOP, in at least some embodiments.

In an embodiment, the medium protection controller 142 is implemented bya processor executing machine readable instructions stored in a memory,where the machine readable instructions cause the processor to performacts described in more detail below. In another embodiment, the mediumprotection controller 142 additionally or alternatively comprises one ormore hardware state machines that are configured to perform actsdescribed in more detail below.

The WLAN 110 includes a plurality of client stations 154. Although threeclient stations 154 are illustrated in FIG. 1 , the WLAN 110 includesother suitable numbers (e.g., 1, 2, 4, 5, 6, etc.) of client stations154 in various embodiments. The client station 154-1 includes a hostprocessor 158 coupled to a network interface device 162. The networkinterface device 162 includes one or more MAC processors 166 (sometimesreferred to herein as “the MAC processor 166” for brevity) and one ormore PHY processors 170 (sometimes referred to herein as “the PHYprocessor 170” for brevity). The PHY processor 170 includes a pluralityof transceivers 174, and the transceivers 174 are coupled to a pluralityof antennas 178. Although three transceivers 174 and three antennas 178are illustrated in FIG. 1 , the client station 154-1 includes othersuitable numbers (e.g., 1, 2, 4, 5, etc.) of transceivers 174 andantennas 178 in other embodiments. In some embodiments, the clientstation 154-1 includes a higher number of antennas 178 than transceivers174, and antenna switching techniques are utilized.

In an embodiment, the network interface device 162 is configured foroperation within a single RF band at a given time. In anotherembodiment, the network interface device 162 is configured for operationwithin two or more RF bands at the same time or at different times. Inan embodiment, the network interface device 162 implements multiple APs(e.g., co-located client stations), respective client stations operatingin respective ones of the frequency bands. For example, in anembodiment, the network interface device 162 includes multiple PHYprocessors 170, where respective PHY processors 170 correspond torespective ones of the co-located client stations for operation inrespective ones of the frequency bands. In another embodiment, thenetwork interface device 162 includes a single PHY processor 170, whereeach transceiver 174 includes respective RF radios corresponding torespective ones of the co-located client stations for operation inrespective ones of the frequency bands. In an embodiment, the networkinterface device 162 includes multiple MAC processors 166, whererespective MAC processors 166 correspond to respective ones of theco-located client stations for operation in respective ones of thefrequency bands. In another embodiment, the network interface device 162includes a single MAC processor 166 corresponding to the multipleco-located client stations for operation in respective ones of thefrequency bands.

The network interface device 162 is implemented using one or more ICsconfigured to operate as discussed below. For example, the MAC processor166 may be implemented on at least a first IC, and the PHY processor 170may be implemented on at least a second IC. The first IC and the secondIC may be packaged together in a single IC package thereby forming amodular device, or the first IC and the second IC may be coupledtogether on a single printed board, for example, in various embodiments.As another example, at least a portion of the MAC processor 166 and atleast a portion of the PHY processor 170 may be implemented on a singleIC. For instance, the network interface device 162 may be implementedusing an SoC, where the SoC includes at least a portion of the MACprocessor 166 and at least a portion of the PHY processor 170.

In an embodiment, the host processor 158 includes a processor configuredto execute machine readable instructions stored in a memory device (notshown) such as a RAM, a ROM, a flash memory, etc. In an embodiment, thehost processor 158 may be implemented, at least partially, on a firstIC, and the network device 162 may be implemented, at least partially,on a second IC. As another example, the host processor 158 and at leasta portion of the network interface device 162 may be implemented on asingle IC.

In various embodiments, the MAC processor 166 and the PHY processor 170of the client station 154-1 are configured to generate data units, andprocess received data units, that conform to the WLAN communicationprotocol or another suitable communication protocol. For example, theMAC processor 166 may be configured to implement MAC layer functions,including MAC layer functions of the WLAN communication protocol, andthe PHY processor 170 may be configured to implement PHY functions,including PHY functions of the WLAN communication protocol. The MACprocessor 166 may be configured to generate MAC layer data units such asMSDUs, MPDUs, etc., and provide the MAC layer data units to the PHYprocessor 170. The PHY processor 170 may be configured to receive MAClayer data units from the MAC processor 166 and encapsulate the MAClayer data units to generate PHY data units such as PPDUs fortransmission via the antennas 178. Similarly, the PHY processor 170 maybe configured to receive PHY data units that were received via theantennas 178, and extract MAC layer data units encapsulated within thePHY data units. The PHY processor 170 may provide the extracted MAClayer data units to the MAC processor 166, which processes the MAC layerdata units.

The PHY processor 170 is configured to downconvert one or more RFsignals received via the one or more antennas 178 to one or morebaseband analog signals, and convert the analog baseband signal(s) toone or more digital baseband signals, according to an embodiment. ThePHY processor 170 is further configured to process the one or moredigital baseband signals to demodulate the one or more digital basebandsignals and to generate a PPDU. The PHY processor 170 includesamplifiers (e.g., an LNA, a power amplifier, etc.), an RF downconverter,an RF upconverter, a plurality of filters, one or more ADCs, one or moreDACs, one or more DFT calculators (e.g., an FFT calculator), one or moreIDFT calculators (e.g., an IFFT calculator), one or more modulators, oneor more demodulators, etc.

The PHY processor 170 is configured to generate one or more RF signalsthat are provided to the one or more antennas 178. The PHY processor 170is also configured to receive one or more RF signals from the one ormore antennas 178.

The MAC processor 166 is configured to control the PHY processor 170 togenerate one or more RF signals by, for example, providing one or moreMAC layer data units (e.g., MPDUs) to the PHY processor 170, andoptionally providing one or more control signals to the PHY processor170, according to some embodiments. In an embodiment, the MAC processor166 includes a processor configured to execute machine readableinstructions stored in a memory device (not shown) such as a RAM, a ROM,a flash memory, etc. In an embodiment, the MAC processor 166 includes ahardware state machine.

The MAC processor 166 includes, or implements, a medium protectioncontroller 192. The medium protection controller 192 implements mediumprotection mechanisms of the AP 114 in at least the first frequency band(e.g., the 6 GHz band). In some embodiments, the medium protectioncontroller 192 additionally implements medium protection mechanisms ofthe AP 114 in one or more additional frequency bands, such as the secondfrequency band (e.g., the 5 GHz band) and/or the third frequency band(e.g., the 2.4 GHz band).

As will be described in more detail below, the medium protectioncontroller 192 generates a control frame (e.g., an RTS frame, a CTSframe, an acknowledgement frame, etc.), and prompts the PHY processor170 to transmit the control frame the AP 114, for example to reserve acommunication channel for transmissions between the client station 154-1and the AP 114. In an embodiment, the medium protection controller 192prompts the PHY processor 170 to transmit the control frame using aparticular PHY data unit format and/or particular transmission rules,where the particular PHY data unit format and/or the particulartransmission rules depend on the particular frequency band in which thecontrol frame is to be transmitted. For example, when the control frameis to be transmitted in the second frequency band or in the thirdfrequency band, the medium protection controller 192 prompts the PHYprocessor 170 to transmit the control frame using a legacy PHY data unitformat and legacy transmission rules. On the other hand, when thecontrol frame is to be transmitted in the first frequency band, themedium protection controller 192 selectively prompts the PHY processor170 to transmit the control frame i) using a legacy PHY data unit format(e.g., a PHY data unit format specified by the fourth communicationprotocol) and legacy transmission rules or ii) using a non-legacy PHYdata unit format and/or non-legacy transmission rules. Transmission ofthe control frame using non-legacy PHY data unit formats and/ornon-legacy transmission rules in the first frequency band results inmore efficient and/or more robust transmission of the control frame inthe first frequency band, for example, as compared to transmission ofcontrol frames in the second frequency band and in the third frequencyband, in at least some embodiments.

In an embodiment, the medium protection controller 192 generatesmultiple frames (e.g., control, management and/or data frames), andprompts the PHY processor to transmit the multiple frames to the AP 114during a transmit opportunity (TXOP) for transmissions between theclient station 154-1 (or a group of client stations 154 of which theclient station 154-1 is a part) and the AP 114. In an embodiment, themedium protection controller 192 determines a bandwidth to be used fortransmission of a frame of the multiple frames, and prompts the PHYprocessor 170 to transmit the frame using a PHY data unit that spans thedetermined bandwidth of the frame. As will be explained in more detailbelow, in at least some situations, the medium protection controller 192determines that a bandwidth of a frame to be transmitted during the TXOPcan be increased with respect to a bandwidth of a previous frametransmitted during the TXOP in at least some situations in which theTXOP is not protected by an initial control frame exchange, thatconforms to a legacy communication protocol (e.g., the fourthcommunication protocol) and that occurred prior to transmission of themultiple frames during the TXOP. For example, in an embodiment, themedium protection controller 192 determines that the wider bandwidth hasbeen reserved for transmissions between the client station 154-1 (or thegroup of client stations 154 of which the client station 154-1 is apart) and the AP 114, for the duration of the TXOP, by previoustransmissions of non-legacy data units during the TXOP. In at least somesuch situations, the medium protection controller 192 generates theframe for transmission in the wider bandwidth, and prompts the PHYprocessor 170 to transmit the frame using a PHY data unit that spans thedetermined wider bandwidth. Because the bandwidth of a frame transmittedduring a TXOP is increased with respect to the bandwidth of a previouslytransmitted frame during the TXOP even if the TXOP is not protected byan initial control frame exchange that conforms to a legacycommunication protocol (e.g., the fourth communication protocol), moreinformation (e.g., management information, data, etc.) can betransmitted during the TXOP as compared to systems in which framebandwidth cannot be increased during the TXOP, in at least someembodiments.

In an embodiment, the medium protection controller 192 is implemented bya processor executing machine readable instructions stored in a memory,where the machine readable instructions cause the processor to performacts described in more detail below. In another embodiment, the mediumprotection controller 192 additionally or alternatively comprises one ormore hardware state machines that are configured to perform actsdescribed in more detail below.

In an embodiment, each of the client stations 154-2 and 154-3 has astructure that is the same as or similar to the client station 154-1. Inan embodiment, one or more of the client stations 154-2 and 154-3 has adifferent suitable structure than the client station 154-1. Each of theclient stations 154-2 and 154-3 has the same or a different number oftransceivers and antennas. For example, the client station 154-2 and/orthe client station 154-3 each have only two transceivers and twoantennas (not shown), according to an embodiment.

FIG. 2 is a diagram of an example PPDU 200 that the network interfacedevice 122 (FIG. 1 ) is configured to generate and transmit to one ormore client stations 154 (e.g., the client station 154-1), according toan embodiment. If the PPDU is transmitted by a client station 154, thenetwork interface device 122 (FIG. 1 ) is also configured to receive andprocess the PPDU 200, according to an embodiment.

The network interface device 162 (FIG. 1 ) is also be configured togenerate and transmit the PPDU 200 to the AP 114, according to anembodiment. If the PPDU is transmitted by the AP 114, the networkinterface device 162 (FIG. 1 ) is also configured to receive and processthe PPDU 200, according to an embodiment.

The PPDU 200 conforms to a legacy physical layer format. In anembodiment, the PPDU 200 is referred to as a non-high-throughput(non-HT) PHY data unit. The PPDU 200 occupies a 20 MHz bandwidth oranother suitable bandwidth, in an embodiment. Data units similar to thePPDU 200 occupy other suitable bandwidths that correspond to anaggregation of multiple component channels (e.g., each having a 20 MHzbandwidth or another suitable bandwidth), in other embodiments.

The PPDU 200 includes a PHY preamble 204. The PHY preamble 204 conformsto a legacy PHY preamble format and includes a legacy short trainingfield (L-STF) 205, a legacy long training field (L-LTF) 210, a legacysignal field (L-SIG) 215, in an embodiment. The L-STF 205 generallyincludes information that is useful for packet detection andsynchronization, whereas the L-LTF 210 generally includes informationthat is useful for channel estimation and fine synchronization. TheL-SIG 215 generally signals PHY parameters to the receiving devices,including legacy devices, such as a length of the PPDU 300. In anembodiment, the PHY preamble 204 is configured to be processed by legacycommunication devices in the WLAN 110 (i.e., communication devices thatoperate according to a legacy communication protocol), enabling thelegacy communication devices to detect the PPDU 200 and to obtain PHYinformation corresponding to the PPDU 200, such as a duration of thePPDU 200. The PPDU 200 also includes a PHY data portion 240, in anembodiment. The PHY data portion 240 includes an MPDU, in an embodiment.In some scenarios, the PPDU 200 may omit the data portion 240.

FIG. 3 is a diagram of an example PPDU 300 that the network interfacedevice 122 (FIG. 1 ) is configured to generate and transmit to one ormore client stations 154 (e.g., the client station 154-1), according toan embodiment. If the PPDU is transmitted by a client station 154, thenetwork interface device 122 (FIG. 1 ) is also configured to receive andprocess the PPDU 300, according to an embodiment.

The network interface device 162 (FIG. 1 ) is also be configured togenerate and transmit the PPDU 300 to the AP 114, according to anembodiment. If the PPDU is transmitted by the AP 114, the networkinterface device 162 (FIG. 1 ) is also configured to receive and processthe PPDU 300, according to an embodiment.

The PPDU 300 includes a preamble 302 including a legacy short trainingfield (L-STF) 305, a legacy long training field (L-LTF) 310, a legacysignal field (L-SIG) 315, a repeated L-SIG field (RL-SIG) 318, a highefficiency (HE) signal field (HE-SIG-A) 320, an HE short training field(HE-STF) 325, and M HE long training fields (HE-LTFs) 330, where M is asuitable positive integer. In an embodiment, M generally corresponds to(e.g., is greater than or equal to) a number of spatial streams viawhich the data unit 300 will be transmitted. A legacy preamble portion342 of the preamble 302 includes the L-STF 305, L-LTF 310 and L-SIG 315.An HE preamble portion 344 of the preamble 302 includes the RL-SIG 318,the HE-SIG-A 320, the HE-STF 325 and the M HE-LTFs 330. The data unit300 also includes a data portion 340. The PHY data portion 340 includesan MPDU, in an embodiment. In some scenarios, the PPDU 300 may omit thedata portion 340.

The L-STF 305 generally includes information that is useful for packetdetection and synchronization, whereas the L-LTF 310 generally includesinformation that is useful for channel estimation and finesynchronization. The L-SIG 315 generally signals PHY parameters to thereceiving devices, including legacy devices, such as a length of thePPDU 300.

The HE-STF 325 generally includes information that is useful forimproving automatic gain control estimation in a MIMO transmission. TheHE-LTFs 330 generally includes information that is useful for estimatinga MIMO channel.

In some embodiments, the preamble 302 omits one or more of the fields305-330. In some embodiments, the preamble 302 includes additionalfields not illustrated in FIG. 2 .

Each of the L-STF 305, the L-LTF 310, the L-SIG 315, the RL-SIG 318, theHE-SIG-A 320, the HE-STF 325, and the M HE-LTFs 330 comprises one ormore OFDM symbols. As merely an illustrative example, the HE-SIG-A 320comprises two OFDM symbols.

In the illustration of FIG. 2 , the PPDU 300 includes one of each of theL-STF 305, the L-LTF 310, the L-SIG 315, the RL-SIG 318 and the HE-SIG-A320. In some embodiments in which a data unit similar to the data unit300 occupies a cumulative bandwidth other than 20 MHz, each of the L-STF305, the L-LTF 310, the L-SIG 315, the RL-SIG 318, and the HE-SIG-A 320is repeated over a corresponding number of 20 MHz sub-bands of the wholebandwidth of the data unit, in an embodiment. For example, in anembodiment in which the data unit occupies an 80 MHz bandwidth, the PPDU300 includes four of each of the L-STF 305, the L-LTF 310, the L-SIG315, the RL-SIG 318, and the HE-SIG-A 320 in respective 20 MHzsub-bands.

In an embodiment, the HE-SIG-A 320 generally carries information aboutthe format of the PPDU 300, such as information needed to properlydecode at least a portion of the PPDU 300, in an embodiment. In someembodiments, HE-SIG-A 320 additionally includes information forreceivers that are not intended receivers of the PPDU 300, such asinformation needed for medium protection, spatial reuse, etc.

In an embodiment, the HE-SIG-A field 320 includes a bandwidth subfield342 and a TXOP subfield 344. The bandwidth subfield 342 includesinformation indicating the bandwidth of the PPDU 300. The TXOP durationsubfield 344 includes information indicating a time duration of aremainder of a TXOP, in which the PPDU 300 is transmitted, aftertransmission of the PPDU 300. In an embodiment, the communication device(e.g., the AP 114 or the client station 154-1) that initiates the TXOP(sometime referred to herein as “TXOP holder”) sets the TXOP subfield344 to a valid value to inform other communication devices of theduration of the TXOP and to reserve the communication channelcorresponding to the bandwidth of the PPDU 300, indicated by thebandwidth subfield 342, for the duration of the TXOP. In somesituations, the TXOP holder sets the TXOP duration subfield 344 toindicate that the TXOP is unspecified, in an embodiment. In suchsituations, the TXOP holder does not reserve the communication channelfor the TXOP, in an embodiment. In an embodiment, the TXOP holder is notpermitted to set the TXOP duration subfield 344 to indicate that theTXOP is unspecified when the PPDU 300 is transmitted in the firstfrequency band unless a valid TXOP duration value is disallowed. In anembodiment, a valid TXOP duration value is disallowed when one or bothof the following conditions are satisfied (i) BSS color is currentlydisabled (e.g., as indicated by a BSS color disabled field in a mostrecent operation element (e.g., HE operation element) transmitted orreceived by the TXOP holder) and (ii) the PPDU 300 includes a power savepoll (PS-Poll) frame. Thus, in an embodiment, when the PPDU 300 istransmitted in the first frequency band, the TXOP holder does not setthe TXOP duration subfield 344 to a value indicating that the TXOP isunspecified unless one or both of the conditions (i) and (ii) aresatisfied.

In some embodiments, a format similar to the format in FIG. 2 is definedfor an extended range SU PPDU, where a duration of an HE-SIG-A field istwice the duration of the HE-SIG-A 320. For example, in an embodiment,information in the HE-SIG-A field 320 is included twice so that theduration of the HE-SIG-A field in the extended range SU PPDU is twicethe duration of the HE-SIG-A 320.

Additionally, for an extended range SU PPDU, transmit power is boostedfor certain fields (and/or certain OFDM tones of certain fields) of thepreamble 302 as compared to a transmit power of other fields/portions ofthe extended range SU PPDU, such as the data portion 340, according tosome embodiments. For example, a transmit power boost of 3 decibels (dB)is applied to one of, or any suitable combination of two or more of,L-STF 305, L-LTF 310, HE-STF 325, and/or HE-LTF(s) 330, as compared to atransmit power of other fields/portions of the extended range SU PPDU,such as the data portion 340, according to some embodiments. Such atransmit power boost to fields such as L-STF 305, L-LTF 310, HE-STF 325,and/or HE-LTF(s) 330, help to improve packet detection, synchronization,channel estimation, etc., for communication devices separated by greaterdistances.

In an embodiment, the AP 114 and a plurality of client stations 154 areconfigured for multiple user (MU) communication using orthogonalfrequency division multiple access (OFDMA) transmissions. In anembodiment, the PPDU 300 is an MU OFDMA data unit in which independentdata streams are transmitted to or by multiple client stations 154 usingrespective sets of OFDM tones allocated to the client stations 154. Forexample, in an embodiment, available OFDM tones (e.g., OFDM tones thatare not used as DC tones and/or guard tones) are segmented into multipleresource units (RUs), and each of the multiple RUs is allocated to datato one or more client stations 154. In an embodiment, the independentdata streams in respective allocated RUs are further transmitted usingrespective spatial streams, allocated to the client stations 154, usingmultiple-input multiple-output (MIMO) techniques. In an embodiment, thePPDU 300 is an MU-MIMO PHY data unit in which independent data streamsare simultaneously transmitted to or by multiple client stations 154using respective spatial streams allocated to the client stations 154.

Referring to FIGS. 2 and 3 , in various embodiments, a communicationdevice (e.g., the AP 114 or the client station 154-1) selectivelyutilizes the PHY format of the PPDU 200 or the PHY format of the PPDU300 to transmit a control frame (e. an RTS frame, a CTS frame, a triggerframe, an acknowledgement frame, etc.). For example, the communicationdevice selectively includes the control frame in the data portion 240 ofthe PPDU 200 when the control frame is to be transmitted in the firstfrequency band, the second frequency band or in the third frequencyband. Referring now to FIG. 3 , the communication device does notutilize the PHY format of the PPDU 300 for transmission of controlframes in the second frequency band or in the third frequency band, inan embodiment. On the other hand, the communication device utilizes thePHY format of the PPDU 300 for transmission of control frames in thefirst frequency band in at least some situations, in an embodiment. Forexample, the communication device includes the control frame in the dataportion 340 of the PPDU 300 when the control frame is to be transmittedin the first frequency band in at least some situations, in anembodiment. In an embodiment, the communication device utilizes SU PHYformat of the PPDU 300 to transmit the control frame in the firstfrequency band. In another embodiment, in at least some situations, thecommunication device utilizes extended range SU PHY format of the PPDU300 to transmit the control frame, for example when the control framecannot be reliably transmitted using the SU PHY format of the PPDU 300.In yet another embodiment, the communication device utilizes MU PHYformat of the PPDU 300 to transmit the control frame. For example, thecommunication device includes the control frame in one or more RUs ofthe PPDU 300, in an embodiment.

In an embodiment, a single user PPDU (the PPDU 200 of FIG. 2 or the SUPHY format of the PPDU 300 of FIG. 3 ) that includes a control framespans a bandwidth no wider the bandwidth of a single component channel(e.g., a 20 MHz component channel) of a communication channel. In someembodiments, to cover multiple component channels of a communicationchannel, a duplicate PHY mode in which duplicates of the control frameare included in respective single user PPDUs that are simultaneouslytransmitted in respective ones of the multiple component channels of thecommunication channel.

FIG. 4A is a diagram of an example transmission sequence 400 that occursduring a TXOP, according to an embodiment. In an embodiment, thetransmission sequence 400 occurs in the first frequency band. In anotherembodiment, the transmission sequence 400 occurs in the second frequencyband or in the third frequency band. The transmission sequence 400includes a frame exchange 402. In an embodiment, the frame exchange is afirst frame exchange of a TXOP and is utilized to negotiate an availablebandwidth to be used for transmissions during the TXOP and to protectthe available bandwidth for the duration of the TXOP. In anotherembodiment, the frame exchange 402 is not the first frame exchange of aTXOP and/or the frame exchanged 402 is not used for bandwidthnegotiation and/or protection. For example, the frame exchange 402occurs during the TXOP after a previous frame exchange that occurredduring the TXOP, in an embodiment.

In the frame exchange 402, a first communication device (e.g., the AP114, the network interface 122, etc.) generates a PPDU 404 and transmitsthe PPDU 404 to at least one second communication device (e.g., at leastone client station 154). The PPDU 404 spans multiple component channels406 of a composite communication channel, in an embodiment. In anembodiment, the component channels 406 spun by the PPDU 404 areconsecutive in frequency as illustrated in FIG. 4 . In anotherembodiment, for example when a punctured communication channel isutilized, a gap exists between at least two of the component channelsspun by the PPDU 404. For example, one of the component channels 406(e.g., the component channel 406-2) is punctured, and therefore thefirst communication device generates the PPDU 404 to span the componentchannel 406-1, 406-3 and 406-4 and transmits the PPDU 404 withouttransmitting anything in the frequency portion corresponding to thepunctured component channel 406-2, in an embodiment.

In an embodiment, at least a PHY preamble of the PPDU 404 is transmittedin each of the component channels 406 spun by the PPDU 404. The at leastthe portion of the preamble transmitted in each of the of the componentchannels 406 is decodable by other communication devices operating inthe component channels of the composite communication channel, in anembodiment. In an embodiment, other communication devices that areoperating in the vicinity of the first communication device and that arenot intended recipients of the PPDU 404 receive at least the portion ofthe PPDU 404 transmitted in component channels 406 in which thecommunication devices are operating, and determine, based on durationinformation included in the at least the portion of the preamble of thePPDU a duration for which the communication channel is reserved by thefirst communication device. The other communication devices then refrainfrom attempting to access communication channel at least for theduration indicated in the PPDU 404, in an embodiment.

The PPDU 404 includes an initiating control frame (e.g., an RTS frame, atrigger frame, a trigger+QoS Null frame, etc.), in an embodiment. Inanother embodiment, the PPDU 404 includes a data frame (e.g., a QoS dataframe, an A-MPDU, etc.) In an embodiment, in a scenario in which theframe exchange occurs in the first frequency band, the PPDU 404 thatincludes the initiating frame corresponds to the PPDU 200 of FIG. 2transmitted in duplicate PHY mode. In another embodiment, in a scenarioin which the frame exchange occurs in the first frequency band, the PPDU404 that includes the initiating frame corresponds to the PPDU 300 ofFIG. 3 transmitted in duplicate PHY mode.

In an embodiment, the first communication protocol permits transmissionof a control frame in the first frequency band using a non-legacy PHYformat, such as the HE SU PPDU format or the HE ER SU format of the PPDU300 if the control frame i) is not solicited by another control frameand i) is not a trigger frame. In this embodiment, because the PPDU 404includes the initiating control frame that is not solicited by any othercontrol frame, the first communication device optionally generates thePPDU 400 to correspond to a non-legacy PHY format, such as the HE SUPPDU format or the HE ER SU format of the PPDU 300 if the initiatingcontrol frame is not a trigger frame, in an embodiment. On the otherhand, if the initiating control frame included in the PPDU 300 is atrigger frame, the first communication device optionally generates thePPDU 400 to correspond to a legacy PHY format such as the PHY format ofthe PPDU 200 of FIG. 2 , in an embodiment. In another embodiment, thefirst communication protocol permits transmission of a control frame inthe first frequency band using a non-legacy PHY format, such as the HESU PPDU format or the HE ER SU format of the PPDU 300 even if thecontrol frame i) is solicited by another control frame and/or i) is atrigger frame.

In an embodiment, the first communication device selects, from among aset of possible PHY formats, a PHY format for the PPDU 404 that includesthe initiating control frame based on one or both of i) the type of theinitiating control frame and ii) PHY format(s) that are supported by oneor more intended recipients of the initiating control frame. Forexample, in an embodiment, if the initiating control frame included inthe PPDU 404 is not a MU-RTS frame, then the first communication deviceselects a PHY format, from among a legacy PHY format and one or morenon-legacy PHY formats, for the PPDU 404, and generates the PPDU 404 toconform to the selected PHY format, where the selected PHY format mustbe supported by the intended recipient(s) of the initiating controlframe. On the other hand, if the initiating control frame included inthe PPDU 404 is an MU-RTS frame, then the first communication devicegenerates the PPDU 404 according to the legacy PHY format even ifintended receipt(s) of the initiating control frame support non-legacyPHY format(s).

In an embodiment, in a scenario in which the frame exchange 402 occursin the second frequency band or the third frequency band, the firstcommunication device generates the PPDU 404 to conform to a legacy PHYformat such as the PHY format of the PPDU 200 of FIG. 2. In anotherembodiment, in a scenario in which the frame exchange 402 occurs in thesecond frequency band or the third frequency band, the firstcommunication device generates the PPDU 404 selectively to conform to alegacy PHY format such as the PHY format of the PPDU 200 of FIG. 2 or anon-legacy PHY format such as the HE SU PPDU format or the HE SU ER PPDUformat of the PPDU 300 of FIG. 3 . For example, in an embodiment, thefirst communication device selectively generates the PPDU 404 thatincludes the initiating control frame that is not a trigger frame toconform to the HE SU PPDU format or the HE ER SU PPDU format if theinitiating control frame is being transmitted using space-time blockcoding (STBC), and generates the PPDU 404 that includes the initiatingcontrol frame that is not a trigger frame to conform to the legacy PHYformat if STBC is not utilized. In an embodiment, the firstcommunication device selectively generates the PPDU 404 that includesthe initiating control frame that is not a trigger frame to conform tothe HE ER SU PPDU format if the intended receipt(s) of the initiatingcontrol frame support the HE ER SU PPDU format and, in some embodiments,only if a PPDU conforming to a non-extended rage PHY format cannotreliably reach the intended receipt(s) of the initiating control frame.

In response to receiving the PPDU 404, a second communication device(e.g., the client station 154-1) that is an intended recipient of theinitiating control frame in the PPDU 404 generates and transmits a PPDU408. In an embodiment, the PPDU 408 includes a responding control frame(e.g., a CTS frame). In another embodiment, the PPDU 408 includes a dataframe. For example, in an embodiment in which the PPDU 404 includes atrigger frame that prompts the at least one second communication deviceto transmit data to the first communication device, the secondcommunication device responds to the trigger frame in the PPDU 404 byincluding data in the PPDU 408 (e.g., in a frequency portion of thecommunication channel allocated to the second communication device asindicated in the trigger frame). In an embodiment, in a scenario inwhich the frame exchange 402 occurs in the second frequency band or thethird frequency band, the second communication device generates the PPDU408 to conform to a legacy PHY format, such as the PHY format of thePPDU 200 of FIG. 2 , and using legacy transmission rules (e.g., using adata rate corresponding to a lowest modulation and coding scheme (MCS),using a single spatial stream, etc.). On the other hand, when the frameexchange 402 occurs in the first frequency band, the secondcommunication device selectively generates the PPDU 408 to conform to anon-legacy PHY format, such as the HE SU PPDU, the HE ER SU PPDU or theHE MU PPDU format of the data unit 300 of FIG. 3 and/or using non-legacytransmission rules (e.g., using a higher MCS).

In an embodiment, the second communication device selects a number ofspatial streams (Nss) and/or a MCS for transmission of the PPDU 408, andtransmits the PPDU 408 using the selected Nss and/or MCS. In anembodiment, the second communication device transmits the PPDU 408 usinga single Nss if the PPDU 408 is not a trigger-based PPDU (e.g., not anHE TB PPDU). In other words, a single Nss is used to transmit the PPDU408 if the PPDU 404 does not include a trigger frame that promptstransmission of the PPDU 408, in an embodiment. In an embodiment, thesecond communication device selects an MCS for transmission of the PPDU408 from a set of MCSs that do not exceed an MCS of the initiatingcontrol frame included in the PPDU 404.

In various embodiments, the PPDU 408 transmitted by the secondcommunication device spans the same bandwidth, or a different bandwidth(e.g., a narrower bandwidth), as the bandwidth of the PPDU 404 that thesecond communication device receives from the first communicationdevice. In an embodiment, the second communication device transmits thePPDU 408 as part of bandwidth negation for the TXOP. For example, inresponse to receiving the PPDU 404, the second communication devicedetermines whether or not the component channels 406 spun by the PPDU404 are idle and available for transmission by the second communicationdevice. In an embodiment, the second communication device determinesthat a component channel 406 is idle if i) the value of a channel accesscounter (e.g., network navigation vector (NAV) timer) is zero and ii)channel sensing (e.g., clear channel assessment) performed by the secondcommunication device for a predetermined time period after reception ofthe PPDU 404 indicates that the component channel is idle. In anembodiment, the predetermined time period is a time period correspondingto a point coordination function (PCF) interframe space (PIFS). Inanother embodiment, the predetermined time period is a short interframespace (SIFS). In another embodiment, another suitable predetermined timeperiod is utilized.

In an embodiment in which static bandwidth negotiation is utilized, thesecond communication device transmits the PPDU 404 that spans thecomponent channels 406 only if the second communication devicedetermines that all component channels 406 are idle and available fortransmission by the second communication device. If, on the other hand,the second communication device determines that one or more of thecomponent channels 406 are not available for transmission by the secondcommunication device, then the second communication device does nottransmit the PPDU 408, in this embodiment. In another embodiment, inwhich dynamic bandwidth negotiation is utilized, the secondcommunication device transmits the PPDU 408 that spans only those one ormore component channels 406 that were determined to be idle andavailable for transmission by the second communication device). In anembodiment, dynamic bandwidth negotiation is performed using a legacyPHY data unit format (e.g., the duplicate non-HT PPDU format) fortransmission of the PPDU 404 and PPDU 408. Other PHY data unit formatsare not permitted for performing bandwidth negotiation, in thisembodiment.

In an embodiment, the first communication device signals to the secondcommunication device the bandwidth of the PPDU 404 and/or whether staticbandwidth negotiation or dynamic bandwidth negotiation should beutilized by the second communication device to respond to the PPDU 404.For example, in an embodiment, the first communication device includesinformation indicating the bandwidth of the PPDU 404 and informationindicating whether static or dynamic bandwidth should be utilized in asignal field (e.g., HE-SIG-A) of the PPDU 404. In another embodiment,the first communication device includes an indication of the bandwidthof the PPDU 404 and/or whether static or dynamic bandwidth should beutilized in a MAC header the PPDU 404. In other embodiments, othersuitable signaling techniques are utilized for signaling the bandwidthof the PPDU 404 and/or whether static bandwidth negotiation or dynamicbandwidth negotiation should be utilized.

FIG. 4B is a diagram of another example transmission sequence 420 thatoccurs during a TXOP, according to another embodiment. In an embodiment,the transmission sequence 420 occurs in the first frequency band. Inanother embodiment, the transmission sequence 420 occurs in the secondfrequency band or in the third frequency band. The transmission sequence420 includes a frame exchange 422. In an embodiment, the frame exchangeis a first frame exchange of a TXOP and is utilized to negotiate anavailable bandwidth to be used for transmissions during the TXOP and toprotect the available bandwidth for the duration of the TXOP. In anotherembodiment, the frame exchange 422 is not the first frame exchange of aTXOP and/or the frame exchanged 422 is not used for bandwidthnegotiation and/or protection. For example, the frame exchange 422occurs during the TXOP after a previous frame exchange that occurredduring the TXOP, in an embodiment.

The frame exchange 422 is generally the same as the frame exchange 402of FIG. 4A except that in the frame exchange 422, an initiating frame istransmitted using a PPDU 424 that corresponds to a non-duplicatenon-legacy PHY format such as the HE SU or the HE ER SU format of thePPDU 300 of FIG. 3 . In this embodiment, the PHY preamble (e.g., the PHYpreamble 302) of the PPDU 424 is duplicated in each component channel406 spun by the PPDU 424, and the data portion of the PPDU 424 spans theentire bandwidth of the PPDU 424, in an embodiment. Similarly, in theframe exchange 422, a response frame is transmitted using a PPDU 428that corresponds to a non-duplicate non-legacy PHY format such as the HESU or the HE ER SU format of the PPDU 300 of FIG. 3 . In thisembodiment, the PHY preamble (e.g., the PHY preamble 302) of the PPDU428 is duplicated in each component channel 406 spun by the PPDU 424,and the data portion of the PPDU 428 spans the entire bandwidth of thePPDU 428, in an embodiment.

FIG. 4C is a diagram of another example transmission sequence 450 thatoccurs during a TXOP, according to another embodiment. In an embodiment,the transmission sequence 450 occurs in the first frequency band. Inanother embodiment, the transmission sequence 450 occurs in the secondfrequency band or in the third frequency band. The transmission sequence450 includes a frame exchange 452. In an embodiment, the frame exchangeis a first frame exchange of a TXOP and is utilized to negotiate anavailable bandwidth to be used for transmissions during the TXOP and toprotect the available bandwidth for the duration of the TXOP. In anotherembodiment, the frame exchange 452 is not the first frame exchange of aTXOP and/or the frame exchanged 452 is not used for bandwidthnegotiation and/or protection. For example, the frame exchange 452occurs during the TXOP after a previous frame exchange that occurredduring the TXOP, in an embodiment.

The frame exchange 452 is generally the same as the frame exchange 402of FIG. 4A except that in the frame exchange 452, an initiating frame istransmitted using a PPDU 424 that corresponds to a non-duplicatenon-legacy PHY format such as the HE SU or the HE ER SU format of thePPDU 300 of FIG. 3 . In this embodiment, the PHY preamble (e.g., the PHYpreamble 302) of the PPDU 454 is duplicated in each component channel406 spun by the PPDU 424, and the data portion of the PPDU 454 spans theentire bandwidth of the PPDU 424, in an embodiment. The initiating fameincluded in the PPDU 454 includes a trigger frame that promptstransmission of a trigger based (TB) PPDU 458 that includes a responseframe, in an embodiment. In this embodiment, the PHY preamble (e.g., thePHY preamble 302) of the PPDU 458 is duplicated in each componentchannel 406 spun by the PPDU 424, and the data portion of the PPDU 428includes one or more respective response frames transmitted by one ormore communication devices in respective ones of the component channel406, in an embodiment

FIG. 5 is a diagram of a transmission sequence 500 in which multipleframe exchanges 502 occur during a TXOP, according to an embodiment.Although three frame exchanges 502 are illustrated in FIG. 5 , thetransmission sequence 500 includes other suitable numbers of frameexchanges (e.g., 2, 5, 6, 7, etc.), in other embodiments. Each of themultiple frame exchanges 502 corresponds to the frame exchange 402 ofFIG. 4 , in an embodiment. In an embodiment, PHY formats andtransmission rules for transmission of PPDUs of the frame exchange 402of FIG. 4 are utilized for transmission of the corresponding PPDUs ineach of the frame exchanges 502. In other embodiment, other suitable PHYformats and/or transmission rules are utilized.

In an embodiment, in a first frame exchange 502-1, a first communicationdevice (e.g., the AP 114) generates and transmits a PPDU 504 to at leastone second communication device. The PPDU 504 corresponds to one of thePPDU 404 of FIG. 4A, the PPDU 424 of FIG. 4B, or the PPDU 454 of FIG.4C, in various embodiments. In another embodiment, the PPDU 504corresponds to a suitable PPDU different from the PPDU 404 of FIG. 4A,the PPDU 424 of FIG. 4B, or the PPDU 454 of FIG. 4C. The PPDU 504includes an initiating frame such as a control frame (e.g., an RTSframe, a trigger frame, etc.) or a data frame, in an embodiment.

In response to receiving the PPDU 504, at least one second communicationdevice (e.g., the client station 154-1) that is an intended recipient ofthe initiating frame included in the PPDU 504 generates and transmits aPPDU 508. The PPDU 508 corresponds to one of the PPDU 408 of FIG. 4A,the PPDU 428 of FIG. 4B, or the PPDU 458 of FIG. 4C, in variousembodiments. In another embodiment, the PPDU 508 corresponds to asuitable PPDU different from the PPDU 408 of FIG. 4A, the PPDU 428 ofFIG. 4B, or the PPDU 458 of FIG. 4C. The PPDU 508 includes a respondingframe such as a control frame (e.g., a CTS frame in response to an RTSframe included in the PPDU 504 or an acknowledgement frame toacknowledge receipt of a data frame in the PPDU 504) and/or includesdata (e.g., in response to a trigger frame included in the PPDU 504), invarious embodiments.

In an embodiment, the PPDU 504 spans a first bandwidth of acommunication channel that includes one or more component channels. ThePPDU 504 includes at least a preamble portion that is duplicated in eachof the one or more component channels spun by the PPDU 504, in anembodiment. The preamble portion includes information indicating thebandwidth of the PPDU 504 and indicating a time duration of a remainderof the TXOP after transmission of the PPDU 504. For example, a signalfield (e.g., HE-SIG-A field 320 in FIG. 3 ) of the PPDU 504 includes abandwidth subfield (e.g., the BW subfield 342 in FIG. 3 ) for indicatingthe bandwidth of the PPDU 504 and a TXOP duration subfield (e.g., theTXOP duration subfield 344 in FIG. 3 ) for indicating the time durationof the remainder of the TXOP after transmission of the PPDU 504, in anembodiment. The value of the TXOP duration subfield in the signal fieldof the PPDU 504 reserves the communication channel corresponding to thebandwidth of the PPDU 504 for the indicated duration, in an embodiment.In an embodiment, the first communication device does not set the TXOPduration subfield to a value that indicates that the TXOP duration isunspecified. In other words, the first communication device sets theTXOP duration subfield to a valid value that indicates a valid durationof the remainder of the TXOP, in an embodiment.

In an embodiment, the PPDU 508 spans a second bandwidth of acommunication channel that includes one or more component channels. Thesecond bandwidth of the PPDU 508 is the same as the first bandwidth ofthe PPDU 504 when static bandwidth negotiation is utilized. On the otherhand, when dynamic bandwidth is utilized, the second bandwidth of thePPDU 508 can be narrower than the first bandwidth of the PPDU 508, forexample in a scenario in which the second communication devicedetermines that one or more of the component channels spun by the PPDU504 are idle and are not available for transmission by the secondcommunication device.

The PPDU 508 includes at least a preamble portion that is duplicated ineach of the one or more component channels spun by the PPDU 508, in anembodiment. The preamble portion includes information indicating thebandwidth of the PPDU 508 and indicating a time duration of a remainderof the TXOP after transmission of the PPDU 508. For example, a signalfield (e.g., HE-SIG-A field 320 in FIG. 3 ) of the PPDU 508 includes abandwidth subfield (e.g., the BW subfield 342 in FIG. 3 ) for indicatingthe bandwidth of the PPDU 508 and a TXOP duration subfield (e.g., theTXOP duration subfield 344 in FIG. 3 ) for indicating the time durationof the remainder of the TXOP after transmission of the PPDU 508, in anembodiment. The value of the TXOP duration subfield in the signal fieldof the PPDU 508 reserves the communication channel corresponding to thebandwidth of the PPDU 504 for the indicated duration, in an embodiment.In an embodiment, the first communication device does not set the TXOPduration subfield to a value that indicates that the TXOP duration isunspecified. In other words, the first communication device sets theTXOP duration subfield to a valid value that indicates a valid durationof the remainder of the TXOP, in an embodiment.

In the frame exchange 502-2 that follows the frame exchange 502-1, thefirst communication device transmits a PPDU 514 to the at least onesecond communication device. In an embodiment, the PPDU 514 includes acontrol frame (e.g., a trigger frame) and/or includes data for the atleast one second communication device. In response to receiving the PPDU514, the at least second communication device generates and transmits aPPDU 518 to the first communication device. The PPDU 518 includes acontrol frame (e.g., an acknowledgement frame) and/or includes data forthe first communication device, in an embodiment.

In an embodiment, the bandwidth of the communication channel of thesecond frame exchange 502-2 (i.e., the bandwidth of the PPDU 514 and thePPDU 518) is reduced relative to the bandwidth of the communicationchannel of the first exchange 502-1 (i.e., the bandwidth of the PPDU 504and the bandwidth of the PPDU 508), in an embodiment. For example, atthe time of transmission of the PPDU 514, the first communication devicedetermines that only a portion of the communication channel of the firstframe exchange 502-1 is now available for transmission by the firstcommunication device.

In the frame exchange 502-3 that follows the frame exchange 502-2, thefirst communication device transmits a PPDU 524 to the at least onesecond communication device. In an embodiment, the PPDU 524 includes acontrol frame (e.g., a trigger frame) and/or includes data for the atleast one second communication device. In response to receiving the PPDU524, the at least second communication device generates and transmits aPPDU 528 to the first communication device. The PPDU 528 includes acontrol frame (e.g., an acknowledgement frame) and/or includes data forthe first communication device, in an embodiment

In an embodiment, at the time of transmission of the PPDU 524, the firstcommunication device determines that the bandwidth of the communicationchannel of the first frame exchange 502-1 is now available fortransmission by the first communication device. The first communicationdevice also determines that PPDUs 504, 508 of the first frame exchange502-1 included valid TXOP duration indications that reserved thecommunication channel corresponding to the bandwidth of the first frameexchange 502-1 for the duration of the TXOP. In response to determiningthat PPDUs 504, 508 of the first frame exchange 502-1 included validTXOP duration indications, the first communication device generates andtransmits the PPDU 524 that spans the bandwidth of the first frameexchange 502-1 that is wider than the bandwidth of the second frameexchange 502-2, in an embodiment.

In response to receiving the PPDU 524 that spans the bandwidth of thefirst frame exchange 502-1 that is wider than the bandwidth of thesecond frame exchange 502-2, the second communication device generatesand transmits the PPDU 528 to span the bandwidth of the first frameexchange 502-1 that is wider than the bandwidth of the second frameexchange 502-2, in an embodiment. Accordingly, the bandwidth of theframe exchange 502-3 is increased with respect to the bandwidth of thesecond frame exchange 502-2, in an embodiment.

FIG. 6 is a diagram of a transmission sequence 600 in which multipleframe exchanges 602 occur during a TXOP, according to an embodiment. Thetransmission sequence 600 is generally the same as the transmissionsequence 500 of FIG. 5 , except that at least one of a PPDU 604 and aPPDU 608 transmitted during a first frame exchange 602-1 does notinclude a valid value that indicates a valid duration of the remainderof the TXOP after transmission of the PPDU, in an embodiment. Forexample, the first communication device sets the TXOP duration subfield344 of the HE-SIG-A field 320 of PPDU 604 to a value that indicates thatthe TXOP duration is unspecified, in an embodiment. Additionally oralternatively, the second communication device sets the TXOP durationsubfield 344 of the HE-SIG-A field 320 of PPDU 608 to a value thatindicates that the TXOP duration is unspecified, in an embodiment.Because at least one of the PPDU 604 and the PPDU 608 transmitted duringa first frame exchange 602-1 does not include a valid value thatindicates a valid duration of the remainder of the TXOP, thecommunication channel corresponding to the first frame exchange 602 inthe transmission sequence 600 is not reserved. Similar to the frameexchange 502-2 of the transmission sequence 500, a second frame exchange602-2 in the transmission sequence 600 spans a bandwidth that is reducedwith respect to the bandwidth of the first frame exchange 602-1.However, unlike the third frame exchange 502-3 of the transmissionsequence 500, bandwidth of the third frame exchange 602-3 cannot beincreased with respect to the bandwidth of the frame exchange 606-2 inthe transmission sequence 600, in an embodiment. For example, at thetime of transmission of the PPDU 624, the first communication devicedetermines one or both of the PPDUs 604, 608 of the first frame exchange602-1 included an unspecified TXOP duration value. In response todetermining that one or both of the PPDUs 604, 608 of the first frameexchange 602-1 included an unspecified TXOP duration value, the firstcommunication device generates and transmits the PPDU 624 that spans thebandwidth of the second frame exchange 602-2 even if the wider bandwidthof the first frame exchange 602-1 is again available for transmission bythe first communication device, in an embodiment.

In an embodiment, when operating in the second frequency band and thethird frequency band, communication devices (e.g., the AP 114 and theclient stations) utilize a legacy channel access mechanism such asenhanced distributed channel access (EDCA) for determining when thecommunication device can transmit in the communication channel. In anembodiment, the legacy channel access mechanism is not used by at leastsome communication devices (e.g., at least client stations 154) whenoperating in the first frequency band. For example, the firstcommunication protocol does not permit the use of the legacy channelaccess mechanism by client stations when operating in the firstfrequency band. In another embodiment, the AP 114 signals to the clientstations 154 whether the client stations 154 are permitted to access thecommunication channel using the legacy channel access mechanism. In anembodiment, in scenarios in which client stations 154 are not permittedto use the legacy channel access mechanism, the client station 154 arepermitted to transmit only when triggered by the AP 114 (e.g., in uplinkMU transmissions triggered by the AP 114).

In some embodiments, a client station (e.g., the client station 154-1)signals to the AP 114 whether the client station supports disabling ofthe legacy channel access mechanism. For example, the client stationincludes an indication of whether the client station supports disablingof the legacy channel access mechanism in a capabilities element (e.g.,HE capabilities element, HE extended capabilities element, etc.) thatthe client station transmits to the AP 114. When the client stationsignals to the AP 114 that the client station does not support disablingof the legacy channel access mechanism, then the client station canutilize the legacy channel access mechanism if the legacy channel accessmechanism is disallowed by the AP 114, in an embodiment.

In an embodiment, the AP 114 disallows the legacy channel accessmechanism in the first frequency band for only those client stationsthat are associated with the AP 114. In another embodiment, both clientstations that are associated with the AP 114 and client stations thatare not associated with the AP 114 are not allowed to utilize the legacychannel access mechanism in the first frequency band. In one suchembodiment, a client station 154 that is not associated with the AP 114performs association (e.g., transmits a probe request frame, anassociation request frame, etc.) using the legacy channel accesstechnique. After associating with the AP 114 using the legacy channelaccess technique, the client station 154-1 disables the legacy channelaccess technique, in an embodiment. In another embodiment, a clientstation 154 that are not associated with the AP 114 performs association(e.g., transmits a probe request frame, an association request frame,etc.) with the AP 114 using a random access channel access techniquesuch as an uplink OFDMA channel access technique. In another embodiment,a client station 154 that are not associated with the AP 114 associateswith the AP 114 in the second frequency band or the third frequency bandin which the legacy channel access technique is allowed, using thelegacy channel access technique. After associating with the AP 114 theclient station 154 switches to the first frequency band and disables thelegacy channel access technique.

In some embodiments in which client station 154 that are not associatedwith the AP 114 utilize the legacy channel access technique to performassociation with the AP 114, the client stations 154 perform theassociation during an association service period announced by the AP114. FIG. 7A is a diagram illustrating a scheme 700 of associationservice periods used in the WLAN 110 of FIG. 1 , according to anembodiment. In scheme 700, the association periods are not periodic. Inan embodiment, the AP 114 announces respective independent associationperiods 704 in each of some or all of management frame (e.g., beaconframe) 702 transmitted by the AP 114. For example, each beacon frame 702includes an indication of a start time and an end time of acorresponding association service period 704, in an embodiment. FIG. 7Bis a diagram illustrating a scheme 750 of association service periodsused in the WLAN 110 of FIG. 1 , according to an embodiment. In thescheme 750, the association service periods are periodic. In anembodiment, the AP 114 announces periodicity of association periods 754in each of some or all of management frame (e.g., beacon frame) 752transmitted by the AP 114. For example, the beacon frame 752-1 includesan indication of a start time of a first association period 954-1, aduration of the first association period 954-1 and a period, or a timeduration between two consecutive association service periods 954. Theassociation service periods 954 occur at the times indicated by thestart time and period indications in the beacon frame 952-1, in anembodiment.

FIG. 8 is a flow diagram of an example method 800 for transmittingmultiple data units in a communication channel, according to anembodiment. In some embodiments, the AP 114 of FIG. 1 is configured toimplement the method 1400. The method 1400 is described, however, in thecontext of the AP 114 merely for explanatory purposes and, in otherembodiments, the method 1400 is implemented by another suitable devicesuch as the client station 154-1 or another suitable wirelesscommunication device.

At block 802, the AP 114 generates (e.g., the network interface device122 generates) a first data unit to be transmitted during a TXOPobtained by the AP 114. In an embodiment, the AP 114 generate the PPDU514 of FIG. 5 . In another embodiment, the AP 114 generates a suitabledata unit different from the PPDU 514 of FIG. 5 . In an embodiment, theAP 114 generates the first data unit to span a first bandwidth. Forexample, the AP 114 generates the first data unit to span a firstbandwidth that spans one or more component channel of the communicationchannel. At block 804, the AP 114 transmits the first data unit duringthe TXOP to at least one client station 154.

At block 806, the AP 114 determines that a second bandwidth of a seconddata unit to be transmitted in the TXOP can be greater than the firstbandwidth of the first data unit transmitted, at block 804, during theTXOP. For example, the AP 114 determines that a larger frequency portionof the communication channel is now idle and available for transmissionby the AP 114 as compared to the time at which the first data unit wastransmitted by the AP 114. In an embodiment, the AP 114 determines thatsecond bandwidth of the second data unit can be greater than the firstbandwidth of the first data unit based on respective values of TXOPduration fields included in respective PHY preambles of one or more dataunits transmitted a previous frame exchange during the TXOP. Forexample, the AP 114 determines that second bandwidth of the second dataunit can be greater than the first bandwidth of the first data unitbased on determining that each data unit transmitted in an initial frameexchange during the TXOP included, in respective PHY preambles of thedata units, valid TXOP duration indications that reserved thecommunication channel corresponding to the bandwidth of the initialframe exchange for the duration of the TXOP. Determining that the secondbandwidth of the second data unit can be greater than the firstbandwidth of the first data unit based on respective values of TXOPduration fields included in data units transmitted during a previousframe exchange that occurred during the TXOP allows the AP 114 toincrease the bandwidth of the second data unit relative to the bandwidthof the first data unit even if the TXOP is not protected by an initialcontrol frame exchange that conforms to a legacy communication protocol,in an embodiment.

At block 808, the AP 114 generates the second data unit. In anembodiment, AP 114 generates the PPDU 524 of FIG. 5 . In anotherembodiment, the AP 114 generates a data unit different from the PPDU 524of FIG. 5 . Block 806 is performed in response to determining, at block804 that the second bandwidth of the second data unit transmitted duringthe TXOP can be greater than the first bandwidth of the first data unittransmitted during the TXOP, in an embedment.

At block 810, the AP 114 transmits the second data unit during the TXOPto the at least one other communication device. In an embodiment,because the second bandwidth of the second data unit is increased withrespect to the first bandwidth of the first data unit transmitted duringthe TXOP, more information (e.g., management information, data, etc.)can be transmitted in the second data unit transmitted during the TXOPas compared to systems in which data unit bandwidth cannot be increasedduring the TXOP unless the TXOP is protected by an initial control frameexchange that conforms to a legacy communication protocol, in at leastsome embodiments.

In various embodiments, a method comprises one of, or any suitablecombination of two or more of, the following features.

Embodiment 1: A method for transmitting multiple data units in acommunication channel includes: generating, at a communication device, afirst data unit to be transmitted during a transmit opportunity (TXOP)obtained by the communication device, the first data unit generated tospan a first bandwidth; transmitting, by the communication device, thefirst data unit during the TXOP to at least one other communicationdevice; determining, at the communication device based on respectivevalues of TXOP duration fields included in respective physical layer(PHY) preambles of one or more data units previously transmitted duringthe TXOP, whether a second bandwidth of a second data unit to betransmitted during the TXOP by the communication device can be greaterthan the first bandwidth of the first data unit transmitted during theTXOP by the communication device; in response to determining that thesecond bandwidth of the second data unit transmitted during the TXOP canbe greater than the first bandwidth of the first data unit transmittedduring the TXOP, generating, at the communication device, the seconddata unit to span the second bandwidth greater than the first bandwidth,and transmitting, by the communication device, the second data unitduring the TXOP.

Embodiment 2: The method of embodiment 1, wherein transmitting thesecond data unit comprises transmitting the second data unit aftertransmitting the first data unit.

Embodiment 3: The method of embodiments 1 or 2, wherein determining thatthe second bandwidth of the second data unit can be greater than thefirst bandwidth of the first data unit includes determining that eachdata unit transmitted during an initial frame exchange of the TXOPincluded, in a signal field included in the PHY preamble of the dataunit, a respective TXOP duration indication set to a duration valueother than an unspecified duration value.

Embodiment 4: The method of any of embodiments 1-3, further comprisingdetermining the second bandwidth of the second data unit such that thesecond bandwidth does not exceed a bandwidth corresponding to theinitial frame exchange during the TXOP.

Embodiment 5: The method of any of embodiments 1-4, wherein generatingthe data unit includes determining a value of a TXOP duration field,wherein setting the TXOP duration field to indicate an unspecified TXOPduration is not allowed unless one or both i) basic service set (BSS)color is currently disabled in a BSS in which the communication deviceis operating and ii) the data unit includes a power save poll (PS-poll)frame, generating the TXOP duration field, including setting the TXOPduration field to the determined value, and generating the data unit toinclude the TXOP duration field.

Embodiment 6: The method of any of embodiments 1-5, further comprising,prior to transmitting the first data unit, transmitting, by thecommunication device to the at least one other communication device, aninitiating data unit that includes an initiating control frame, andreceiving, from the at least one other communication device, aresponding data unit that includes a response to the initiating controlframe.

Embodiment 7: The method of embodiment 6, wherein the communicationdevice supports operation according to a first communication protocoland a second communication protocol that is legacy with respect to thefirst communication protocol, and transmitting the initiating data unitcomprises transmitting the initiating data unit using a non-legacy PHYdata unit specified by the first communication protocol and notspecified by the second communication protocol.

Embodiment 8: The method of embodiment 7, wherein transmitting theinitiating data unit using a non-legacy physical layer (PHY) data unitformat comprises transmitting the initiation data unit using an extendedrange PHY data unit format that extends a range of the initiating dataunit with respect to ranges of legacy data units transmitted usinglegacy PHY data unit formats.

Embodiment 9: The method of embodiment 6, wherein the communicationdevice supports operation according to a first communication protocoland a second communication protocol that is legacy with respect to thefirst communication protocol, and receiving the responding data unitcomprises receiving the initiating data unit transmitted using anon-legacy PHY data unit specified by the first communication protocoland not specified by the second communication protocol.

Embodiment 10: The method of embodiment 9, wherein receiving theresponding data unit comprises receiving the initiating data unittransmitted using an extended range PHY data unit format that extends arange of the initiating data unit with respect to ranges of legacy dataunits transmitted using legacy PHY data unit formats.

Embodiment 11: A communication device comprises a network interfacedevice having one or more integrated circuit (IC) devices configured to:generate a first data unit to be transmitted during a transmitopportunity (TXOP) obtained by the communication device, the first dataunit generated to span a first bandwidth, transmit the first data unitduring the TXOP to at least one other communication device, determine,based on respective values of TXOP duration fields included inrespective physical layer (PHY) preambles of one or more data unitspreviously transmitted during the TXOP, that a second bandwidth of asecond data unit to be transmitted during the TXOP by the communicationdevice can be greater than the first bandwidth of the first data unittransmitted during the TXOP by the communication device, in response todetermining that the second bandwidth of the second data unittransmitted during the TXOP can be greater than the first bandwidth ofthe first data unit transmitted during the TXOP, generate the seconddata unit to span the second bandwidth greater than the first bandwidth,and transmit the second data unit during the TXOP.

Embodiment 12: The communication device of embodiment 11, wherein theone or more IC devices are configured to transmit the second data unitafter transmitting the first data unit.

Embodiment 13: The communication device of embodiments 11 or 12, whereinthe one or more IC devices are configured to determine that the secondbandwidth of the second data unit can be greater than the firstbandwidth of the first data unit at least by determining that each dataunit transmitted during an initial frame exchange of the TXOP included,in a signal field of the PHY preamble of the data unit, a respectiveTXOP duration indication set to a duration value other than anunspecified duration value.

Embodiment 14: The communication device of any of embodiments 11-13,wherein the one or more IC devices are further configured to determinethe second bandwidth of the second data unit such that the secondbandwidth does not exceed a bandwidth of the initial frame exchangeduring the TXOP.

Embodiment 15: The communication device of any of embodiments 11-14,wherein the one or more IC devices are further configured to determine avalue of a TXOP duration field, wherein setting the TXOP duration fieldto indicate an unspecified TXOP duration is not allowed unless one orboth i) basic service set (BSS) color is currently disabled in a BSS inwhich the communication device is operating and ii) the data unitincludes a power save poll (PS-poll) frame, generate the TXOP durationfield, including setting the TXOP duration field to the determinedvalue, and generate the data unit to include the TXOP duration field.

Embodiment 16: The communication device of any of embodiments 11-15,wherein the one or more IC devices are further configured to, prior totransmitting the first data unit, transmit, to the at least one othercommunication device, an initiating data unit that includes aninitiating control frame, and receive, from the at least one othercommunication device, a responding data unit that includes a response tothe initiating control frame.

Embodiment 17: The communication device of embodiment 16, wherein thecommunication device supports operation according to a firstcommunication protocol and a second communication protocol that islegacy with respect to the first communication protocol, and the one ormore IC devices are configured to transmit the initiating data unitusing a non-legacy PHY data unit specified by the first communicationprotocol and not specified by the second communication protocol.

Embodiment 18: The communication device of embodiment 17, wherein theone or more IC devices are configured to transmit the initiation dataunit using an extended range PHY data unit format that extends a rangeof the initiating data unit with respect to ranges of legacy data unitstransmitted using legacy PHY data unit formats.

Embodiment 19: The communication device of embodiment 16, wherein thecommunication device supports operation according to a firstcommunication protocol and a second communication protocol that islegacy with respect to the first communication protocol, and the one ormore IC devices are configured to receive the initiating data unittransmitted using a non-legacy PHY data unit specified by the firstcommunication protocol and not specified by the second communicationprotocol.

Embodiment 19: The communication device of embodiment 19, wherein theone or more IC devices are configured to receive initiating data unittransmitted using an extended range PHY data unit format that extends arange of the initiating data unit with respect to ranges of legacy dataunits transmitted using legacy PHY data unit formats.

At least some of the various blocks, operations, and techniquesdescribed above may be implemented utilizing hardware, a processorexecuting firmware instructions, a processor executing softwareinstructions, or any combination thereof. When implemented utilizing aprocessor executing software or firmware instructions, the software orfirmware instructions may be stored in any suitable computer readablememory such as a random access memory (RAM), a read only memory (ROM), aflash memory, etc. The software or firmware instructions may includemachine readable instructions that, when executed by one or moreprocessors, cause the one or more processors to perform various acts.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, an integrated circuit, an application-specificintegrated circuit (ASIC), a programmable logic device (PLD), etc.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, changes, additions and/or deletions may bemade to the disclosed embodiments without departing from the scope ofthe invention.

What is claimed is:
 1. A method for communicating in a wireless localarea network (WLAN), the method comprising: determining, at acommunication device, whether a physical layer (PHY) data unit is to betransmitted in a first frequency band from among multiple frequencybands in which a WLAN communication protocol permits operation, whereinthe multiple frequency bands includes at least a second frequency band;determining, at the communication device, whether the PHY data unit isto include a power save poll (PS-Poll) frame; determining, at thecommunication device, whether a basic service set (BSS) color iscurrently disabled for the WLAN; in response to i) determining that thePHY data unit is to be transmitted in the first frequency band, ii)determining that the PHY data unit is not to include a PS-Poll frame,and iii) determining that the BSS color is not currently disabled forthe WLAN: determining, at the communication device, that a transmitopportunity (TXOP) duration subfield in a PHY preamble of the PHY dataunit cannot be set to a value defined by the WLAN communication protocolfor indicating a TXOP duration that is unspecified, and generating, atthe communication device, the PHY data unit so that the TXOP durationsubfield is set to a duration value that is different than the valuedefined by the WLAN communication for indicating the TXOP duration thatis unspecified; and transmitting, by the communication device, the PHYdata unit in the first frequency band.
 2. The method of claim 1, whereingenerating the PHY data unit so that the TXOP duration subfield is setto the duration value that is different than the value defined by theWLAN communication for indicating the TXOP duration that is unspecifiedcomprises: setting the TXOP duration subfield to a value thatcorresponds to a remaining duration of a TXOP in the WLAN.
 3. The methodof claim 1, wherein generating the PHY data unit so that the TXOPduration subfield is set to the duration value that is different thanthe value defined by the WLAN communication for indicating the TXOPduration that is unspecified comprises: generating the PHY data unit toinclude the TXOP duration subfield in a signal field of the PHYpreamble.
 4. The method of claim 1, further comprising, in response todetermining that the PHY data unit is to include a PS-Poll frame:generating, at the communication device, the PHY data unit to includethe PS-Poll frame; and generating, at the communication device, the PHYdata unit so that the TXOP duration subfield is set to the value definedby the WLAN communication for indicating the TXOP duration that isunspecified.
 5. The method of claim 1, further comprising, in responseto determining that the BSS color is currently disabled for the WLAN:generating, at the communication device, the PHY data unit so that theTXOP duration subfield is set to the value defined by the WLANcommunication for indicating the TXOP duration that is unspecified. 6.The method of claim 1, wherein determining whether the BSS color iscurrently disabled for the WLAN comprises: receiving, at thecommunication device, information from another communication device thatindicates whether the BSS color is currently disabled for the WLAN. 7.The method of claim 1, wherein determining whether the PHY data unit isto be transmitted in the first frequency band comprises determiningwhether the PHY data unit is to be transmitted in a 6 GHz frequencyband, and wherein the second frequency band is one of i) a 2.4 GHzfrequency band and ii) a 5 GHz frequency band.
 8. The method of claim 1,further comprising: determining, at the communication device, afrequency bandwidth, from among a plurality of frequency bandwidthspermitted by the WLAN communication protocol, at which the PHY data unitis to be transmitted; generating, at the communication device, the PHYdata unit to include an indication of the determined frequency bandwidthin a bandwidth subfield in the PHY preamble of the PHY data unit; andgenerating, at the communication device, the PHY data unit to span thedetermined frequency bandwidth.
 9. The method of claim 8, whereingenerating the PHY data unit to include the indication of the determinedfrequency bandwidth in the bandwidth subfield in the PHY preamblecomprises: generating the PHY data unit to include the indication of thedetermined frequency bandwidth in a bandwidth subfield in a signal fieldof the PHY preamble.
 10. A communication device, comprising a wirelessnetwork interface device having one or more integrated circuit (IC)devices, wherein the wireless network interface is configured to:determine whether a physical layer (PHY) data unit is to be transmittedin a first frequency band from among multiple frequency bands in which awireless local area network (WLAN) communication protocol permitsoperation, wherein the multiple frequency bands includes at least asecond frequency band, determine whether the PHY data unit is to includea power save poll (PS-Poll) frame, determine whether a basic service set(BSS) color is currently disabled for a WLAN in which the communicationdevice is operating, in response to i) determining that the PHY dataunit is to be transmitted in the first frequency band, ii) determiningthat the PHY data unit is not to include a PS-Poll frame, and iii)determining that the BSS color is not currently disabled for the WLAN:determine that a transmit opportunity (TXOP) duration subfield in a PHYpreamble of the PHY data unit cannot be set to a value defined by theWLAN communication protocol for indicating a TXOP duration that isunspecified, and generate the PHY data unit so that the TXOP durationsubfield is set to a duration value that is different than the valuedefined by the WLAN communication for indicating the TXOP duration thatis unspecified; wherein the wireless network interface is furtherconfigured to transmit the PHY data unit in the first frequency band.11. The communication device of claim 10, wherein the wireless networkinterface is configured to: in response to i) determining that the PHYdata unit is to be transmitted in the first frequency band, ii)determining that the PHY data unit is not to include a PS-Poll frame,and iii) determining that the BSS color is not currently disabled forthe WLAN, set the TXOP duration subfield to a value that corresponds toa remaining duration of a TXOP in the WLAN.
 12. The communication deviceof claim 10, wherein the wireless network interface is configured to:generate the PHY data unit to include the TXOP duration subfield in asignal field of the PHY preamble.
 13. The communication device of claim10, wherein the wireless network interface is configured to, in responseto determining that the PHY data unit is to include a PS-Poll frame:generate the PHY data unit to include the PS-Poll frame; and generatethe PHY data unit so that the TXOP duration subfield is set to the valuedefined by the WLAN communication for indicating the TXOP duration thatis unspecified.
 14. The communication device of claim 10, wherein thewireless network interface is configured to, in response to determiningthat the BSS color is currently disabled for the WLAN: generate the PHYdata unit so that the TXOP duration subfield is set to the value definedby the WLAN communication for indicating the TXOP duration that isunspecified.
 15. The communication device of claim 10, wherein thewireless network interface is configured to: determine whether the BSScolor is currently disabled for the WLAN based on receiving informationfrom another communication device that indicates whether the BSS coloris currently disabled for the WLAN.
 16. The communication device ofclaim 10, wherein the wireless network interface is configured todetermine whether the PHY data unit is to be transmitted in the firstfrequency band by determining whether the PHY data unit is to betransmitted in a 6 GHz frequency band, and wherein the second frequencyband is one of i) a 2.4 GHz frequency band and ii) a 5 GHz frequencyband.
 17. The communication device of claim 10, wherein the wirelessnetwork interface is further configured to: determine a frequencybandwidth, from among a plurality of frequency bandwidths permitted bythe WLAN communication protocol, at which the PHY data unit is to betransmitted; generate the PHY data unit to include an indication of thedetermined frequency bandwidth in a bandwidth subfield in the PHYpreamble of the PHY data unit; and generate the PHY data unit to spanthe determined frequency bandwidth.
 18. The communication device ofclaim 17, wherein the wireless network interface is configured to:generate the PHY data unit to include the indication of the determinedfrequency bandwidth in a bandwidth subfield in a signal field of the PHYpreamble.
 19. The communication device of claim 10, wherein the wirelessnetwork interface comprises: one or more wireless transceivers.
 20. Thecommunication device of claim 19, further comprising: one or moreantennas coupled to the one or more wireless transceivers.